Expansion at other Detroit area airports is virtually impossible due to constraints beyond the control of those airports. Problems such as congested airspace (regulated by the FAA through Air Traffic Control) or restrictions on land usage in areas contiguous to airports are virtually insurmountable.
The Airport Capacity Enhancement Plan suggests the addition of two new runways at Metro. Most of the land these runways would be built on is already owned by the airport. There are no physical constraints to constructing these runways such as topography, tall buildings, or residential neighborhoods. Therefore, land usage issues will not prevent the expansion of the infrastructure at Metro.
The plan also contains recommendations for modifications in air traffic control procedures which would eliminate many of the delays which occur at present. Air traffic control delays are relatively small compared to delays resulting from the need for an additional east/west runway. (In fact, some of the air traffic control delay is also caused by the absence of a such a runway.} Other plan recommendations would eliminate air traffic control as a significant factor in capacity constraints even with as much as a 50% increase in operations.